Opening Any Excel 2010 file get error 1004 Application defined or Object defined error

Hello, perhaps someone here can help me.

I've looked within the forum and while there appear to be quite a few error 1004 problems, the ones listed don't seem to be right for me. Let's put it this way: if I try to open an Excel 2010 file either new or to edit an existing file, I get the "1004 application defined or object defined error" 3 times before it will open the file. It is not a debilitating error...just annoying and made more-so by the fact that Windows 7 makes the error a pop-under so our staff has to watch closely to see why the file they clicked on isn't opening. They're used to the pop-under now so they know to close the alerts. The thing is, they are Standard Users and cannot add programs willy-nilly to their computers so I wonder how this started. It's been happening for a couple of months now...since before the last IT Guy left. He's the one who brought it to my attention. I strongly doubt sabotage on his part. So far, I have not found what I need on the Internet.

Thank you in advance for any help you can offer.

If I click on the Office 2010 icon to open Excel to a brand new workbook I still get this error. The person with this problem is not in today but I will look at his options to see if he inadvertently changed anything. The only thing is, he won't be back to the office until next week so I won't be able to test it any earlier than then. Still, thanks for the suggestion.